Gauges, such as pressure gauges, are commonly used in various technological fields for a variety of purposes, such as refrigeration, measuring force, measuring contents left in a cylinder, measuring water pressure, line pressure, etc. Such gauges generally include a pointer moveable relative to a calibrated dial. By way of example, refrigeration technology often requires the introduction of one or more refrigerants into apparatus. This procedure is somewhat dangerous, and requires pressure and temperature monitoring. Monitoring is usually accomplished with a manifold gauge assembly comprising a high pressure gauge and a low pressure gauge attached to a common manifold to allow for simultaneous high and low pressure monitoring. The gauges also include a temperature scale; each refrigerant having a particular pressure/temperature relationship. However, the particular temperature scales used on the gauge dials vary, and are a function of the identity of the refrigerant. For environmental reasons, recently there have been used a large number of different refrigerants, thereby requiring an equal number of temperature scales. However, the physical size of the gauge face usually prohibits or inhibits the provision of many multiple scales thereon.
Since it is impracticable and uneconomical to have a different gauge for each refrigerant, various methods have been contemplated for providing a single gauge adaptable to various refrigerants. For example, a universal scale can be used, with appropriate conversion factors available depending upon the particular refrigerant. However, this procedure is tedious and inconvenient, and requires that the operator always have available the appropriate conversion charts for the specific refrigerant being used. It is also prone to operator error.
U.S. Pat. No. 5,471,881 discloses a lenticular gauge face which incorporates multiple reference scales on a single standard manifold gauge face. Thus, a lenticular film is laminated over a gauge face image containing two different temperature scale images. Angling of the gauge allows viewing of one or the other of the distinct images.
U.S. Pat. No. 5,679,903 discloses a refrigerant monitoring set including a manometer and a transparent disk mountable on the outside of the windowed Lace of the manometer housing. The transparent disk includes at least one temperature dial for a given refrigerant which can be assigned to a pressure dial on the manometer face by means of zero-position alignment.
However, the foregoing solutions suffer from various drawbacks, including cost, difficulty in obtaining accurate readings, etc. Nor are these problems limited to gauges used in refrigeration.
It would therefore be desirable to provide a means for providing multiple reference scales on a single gauge or manifold without the concomitant problems of the prior art.